Table 20 



Dog Bar Breakwater 



Gloucester Harbor, Mass. 



Date(s) Construction and Rehabilitation History 



1894- The 2,250-ft-long Dog Bar breakwater, consisting of a rubble stone 

 1906 substructure below mlw and a stone-block superstructure, was con- 

 structed to protect Gloucester Harbor from sea and heavy swells from 

 the south (Figure 23, plan view). The rubble-mound substructure was 

 built to an elevation of ft mlw, where the mound width was 31 ft, 

 a harbor side slope of 1 V : 1 . 3H, and a composite sea-side slope of 

 1V:1.5H and 1V:3H below and above -12 ft mlw, respectively. The 

 substructure stone sizes ranged from 500 lb to 4 tons, except on the 

 seaward side slope where the stone weighed 3 to 5 tons. The super- 

 structure was built up at 1V:0.7H side slopes to an elevation of 

 +17 ft mlw where the crown width was 10 ft. The stone blocks were 

 placed horizontally, in overlapping stair-step fashion, with their 

 lengths perpendicular to the breakwater axis. The blocks were 2 to 

 3 ft high, 2 to 6 ft wide, 7 to 10 ft long, and weighed 3 to 12 tons 

 each. A row of rubble stone, weighing about 5 tons each, was placed 

 along the superstructure seaward toe. A total of 231,760 tons of 

 stone was placed for a total cost of $398,000. 



1931- Minor repairs were made to the superstructure in 1931, 1933-34, 1935, 

 1940 1939, and 1940. The work (approximate totals in parentheses) in- 

 cluded resetting (2,000 tons) and replacing (1,000 tons) stone 

 blocks, placing rubble stone (7,000 tons) on the seaward face 

 (Figure 23, inset), and placing iron pins (700) on the harbor side 

 stone blocks to act as buttressing for the upper courses of stone. 

 The total repair costs were $35,700. 



1962 A breakwater inspection showed the stone block superstructure was in 

 good condition with only localized areas needing repair. The sea- 

 side armor stone, placed during 1931-40, was in poor condition with 

 several large cavities and a general subsidence along the entire 

 breakwater length. 



1965- Repairs were made to the breakwater superstructure, and 10,920 tons 

 1966 of 6- to 12-ton armor stone were placed on the sea side between 0+00 

 (landward end) and 21+85. Displaced stone blocks were reset from 

 1+14 to 1+72 and 9+96 to 10+22. Total cost of the repairs was 

 $96,400. 



1967- Breakwater inspections, taken over this period, showed a gradual 

 1978 deterioration of the sea-side armor stone at several locations. Most 

 of the damage was on the outer half of the breakwater. 



(Continued) 



47 



